The present invention relates to a method for preventing or reducing formation of magnetism in two adjacently located saw blades rotating in opposed rotary directions in relation to each other, and a device for utilization of the method
SE, B, 458 096 discloses a pair of saw blades, comprising two in relation to each other adjacently located saw blades, arranged while rotating in relation to each other opposed rotary directions to take up a saw cut in a workpiece in a common and interacting operation. According to this prior patent publication internal contact between the saw blades is prevented by application of a pneumatic or hydraulic pressure Ad between the saw blades. To accomplish such a pneumatic pressure, it is proposed that each saw blade is arranged with embossed portions from an outer side plane, arranged to form channels open against the rotary direction. Further improvements of such an interacting pair of saw blades are proposed in SE Patent Appln. No. 9403767-8, primarily intended to improve the cut surface of a workpiece and to reduce burr formation, but also this embodiment is based on that the pair of interacting saw blades are maintained separated by application of a pneumatic or hydraulic pressure.
However, practical use of the above mentioned previously known saw blades has resulted in a previously unknown and non-desirable technical effect. The adjacently located and in relation to each other opposed directions rotating saw blades have been magnetized in use, and since adjacent surfaces have a machined plane surface, the saw blades have when used magnetically adhered to each other with such a force, that they hardly not have been separable from each other. The successively increased magnetization during operation has also resulted in a considerable rotary speed reduction, and the sawing operation has been interrupted in certain cases. During the starting operation, a certain xe2x80x9cwobbling effectxe2x80x9d has been observed for the saw blades, i.e. oscillations which during an initial stage result in a wider saw cut.
The object of the present invention is to disclose a method for reducing formation of magnetism in a pair of saw blades of the above mentioned type, which during a starting phase also results in that the adjacently located saw blades move in a parallel relationship, without the above mentioned oscillating movements in relation to each other. The invention also relates to a device for utilization of the method.
The method according to the present invention for preventing or reducing formation of magnetism in two adjacently located saw blades rotating in opposed rotary directions in relation to each other is mainly characterized in that each saw blade is arranged having a number of substantially radially extending through grooves having an extension within the area of the rotary centre for each saw blade and the surrounding saw teeth area, arranged when rotating to remove air existing between adjacent planes of the saw blades, and thereby prevent or reduce magnetization of the saw blades.
The device for utilization of the method according to the present invention is mainly characterized in that each saw blade is arranged having a number of substantially radially extending through grooves having an extension within the area of the rotary centre for each saw blade and the surrounding saw teeth area, arranged when rotating to remove air existing between adjacent planes of the saw blades.